There is an increasing demand for genotyping technology to more efficiently detect DNA variations. For example, efficient, fast and cost-effective techniques are still required for analyses of single nucleotide polymorphisms (SNPs) and known mutations associated with disease. Many methods have been developed for SNP/mutation genotyping. DNA-chip methods based on hybridization have the capability of processing large number of samples, but require careful calibration of the signal when interpreting data. Variants can be detected using single base extension (SBE) followed by separation with capillary electrophoresis using an automated sequencing instrument. However, the length of the extension primer that can be synthesized by the present technology limits the number of samples that can be analyzed in a single capillary. For instance, about 6 SBE products or less are separated in a single capillary using the Applied Biosystems' SNaPshot kit (from Protocol of ABI Prism SNaPshot Multiplex Kit, 2000). Detection of SBE reactions by mass spectrometry requires highly purified products, which can be costly and labor-intensive.